A precombustion-chamber type gas engine is used as an engine for power generation, for instance. A precombustion-chamber type gas engine includes a main chamber (main combustion chamber) defined between a piston and a cylinder head, and a precombustion chamber which is in communication with the main chamber via an injection nozzle, and performs the following combustion flow.
First, fuel gas is supplied to the precombustion chamber from a precombustion-chamber gas supply passage. Next, lean premixed gas in the main chamber flows into the precombustion chamber via an injection nozzle during the compression stroke and is mixed with fuel gas in the precombustion chamber, and the mixture ratio becomes a stoichiometric mixture ratio immediately before ignition. Further, the ignition plug sparks in the precombustion chamber, and flame propagation combustion occurs in the precombustion chamber. The combustion gas produced in the precombustion chamber is injected into the main chamber via the injection nozzle as a torch, and combusts the air-fuel mixture in the main chamber through torch combustion and flame propagation combustion.
With the above precombustion-chamber type gas engine, combustion of the lean premixed gas in the main chamber is combustion at a relatively low temperature. Thus, it is possible to reduce the generation amount of NOx or the like, and reduce pollution. Further, though the air-fuel mixture in the main chamber is lean premixed gas, a torch having a considerable amount of energy is injected, and thus it is possible to complete combustion in the main chamber quickly.
Patent Document 1 discloses a precombustion-chamber type gas engine as described above, which includes a precombustion-chamber gas supply passage capable of supplying fuel gas from a supply source of fuel gas, a check valve disposed in the precombustion-chamber gas supply passage and configured to block a reverse flow of fuel gas from the precombustion-chamber gas supply passage, and a supply pressure control valve disposed upstream of the check valve in the precombustion-chamber gas supply passage and capable of adjusting the pressure of the fuel gas supplied to the precombustion chamber.
The precombustion-chamber type gas engine disclosed in Patent Document 1 includes a valve-open timing and valve-open period detection device for detecting the valve-open timing and the valve-open period of the check valve, and adjusts the supply pressure of fuel gas on the basis of the detection values of the valve-open timing and the valve-open period, so as to improve operation efficiency and suppress combustion variation.